Carbosilane dendrimers comprising Si-O-metal bonds, a method of preparing them and their use

Carbosilane dendrimers comprising Si--O-metal bonds, of general formula

• K›(CH.sub.2).sub.n SiX.sub.a R.sub.3-a !.sub.i
• where n=2, 3, 4, 5 or 6 and R=C.sub.1 -C.sub.18 alkyl or C.sub.6 -C.sub.18 aryl, wherein n and also R can be the same or different within the molecule, and wherein the other symbols and subscripts have the following meanings:
• A) K=›R.sub.4-i Si!
• where i=3 or 4, or ##STR3## where i=m and m=3, 4, 5 or 6, in combination with
• X=--OM when a=1,
• or
• X=›(CH.sub.2).sub.n Si(OM)R.sub.2 !, ›(CH.sub.2).sub.n SiR.sub.3-a ›(CH.sub.2).sub.n Si(OM)R.sub.2 !.sub.a !
• and/or
• ›(CH.sub.2).sub.n SiR.sub.3-a ›(CH.sub.2) .sub.n SiR.sub.3-a ›(CH.sub.2).sub.n Si(OM)R.sub.2 !.sub.a !.sub.a ! when a=1, 2 or 3, where
• M is a metalloid or metal which may optionally contain further substituents and M may be the same or different within the molecule.